The present invention relates to an aqueous crosslinkable resin composition, and more particularly to an aqueous crosslinkable resin composition which is suitable as surface coating materials or under coating materials for papers, woods, metals, plastics or inorganic materials, and as impregnation processing materials or binders for papers, fibers and the like.
Conventionally, surface coating materials and under coating materials have been required to be aqueous system from the viewpoint of danger of fire or safety and sanitation in working, and to be non-formalin system which does not generate formaldehyde from the viewpoint of safety and sanitation of processed products. In consideration of the safety and sanitation, epoxy resins or acrylic resins have been generally employed as the surface coating material and the like.
The epoxy resins themselves have excellent properties such as water resistance, chemical resistance and adhesiveness to substrates or materials, but they do not always exhibit sufficiently these properties in an aqueous system such as an aqueous solution or an aqueous dispersion.
The acrylic resins are inferior to thermosetting resins such as melamine resin, epoxy resin, polyurethane resin in properties such as solvent resistance and water resistance. In order to improve these properties, it has been attempted to modify the acrylic resins, for example, by introducing a reactive group such as carboxyl group, methylol group, amido group, amino group or epoxy group into the acrylic resins, so reacting the reactive group with each other or with other compounds, e.g. melamine resin, epoxy resin, isocyanate compound or aziridine compound. However, such modified acrylic resins are still insufficient in solvent resistance and water resistance.
It is an object of the present invention to provide an aqueous crosslinkable resin composition which is suitable as surface coating material, under coating material, impregnation treating material or binder and which has no danger of producing formaldehyde and has excellent properties such as solvent resistance, water resistance, thermal discoloration resistance, chemical resistance and adhesiveness to substrates.
A further object of the present invention is to provide an aqueous resin composition having a good curability and a long pot life.
These and other objects of the present invention will become apparent from the description hereinafter.